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Teaching in LA

10 Feb

Waves on paper

Posted in Uncategorized on 10.02.13 by Frank

You will be working in pairs. Each pair needs:

  • 1 index card with slits cut in it (see image below)
  • 4 strips of paper (see image below)

In your pairs, set up your index card with one strip of paper like so:

waves_on_paper
(Click to enlarge)

Here are your directions:
Waves on paper

(This is also a good time to check for understanding whether your students can distinguish between wave frequency and wave speed (velocity). Often, students lump the two together in the description, “it’s fast”.)

You should end up with 4 strips of paper.

Look at the two strips you labeled “Low frequency” and “High frequency”. Do they have the same wavelengths or different wavelengths? Which one has shorter wavelengths? Why? Would we say that the frequency of a wave and wavelength of a wave are directly proportional or inversely proportional?

Now, look at the two strips you labeled “Low speed” and “High speed”. Do they have the same wavelengths or different wavelengths? Which one has longer wavelengths? Why? Would we say that the speed of a wave and wavelength of a wave are directly proportional or inversely proportional?

How does this experiment relate to our wave equation, wavelength = velocity/frequency?

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